This invention relates to wood-working machines, and more particularly to what is referred to herein as a slabbing chipper.
A chipper constructed pursuant to the present invention may include a power-rotated head which is disposed to one side of a support for an elongate work piece, such as a log. The head supports knife structures on its periphery which operate to chip off wood material on a log with relative longitudinal movement of a log across the end of the head. In a chipper as just described, the knife structures on the head move in sweeps across the side of the log to produce the chipping action.
Log slabbing chippers are known wherein each knife structure on the power-rotated head comprises a pair of double-edged knives. Each knife has one edge disposed in an operative, cutting position, and an opposite edge disposed in an inoperative position. With wear occurring in a knife, the knife can be turned to change the edge in the knife which is in an operative position. In the chipper being described, the operative cutting edge of one knife with rotation of the head moves in what might be thought of as a conical path, with cutting off of chips as the head is rotated. The operative cutting edge in the other knife moves generally in a plane, and functions to smooth or plane a flat surface on the log as the chips are cut away. A log slabbing chipper with multiple knife structures where each includes a pair of double-edged knives, as above described, is more fully disclosed in prior issued U.S. Pat. No. 5,271,442.
Difficulties have been encountered in a log slabbing chipper which includes knives with operative edges moving as just described, in the handling of logs of small diameter. Speaking in very general terms, with small logs, the aggressive cutting action of the knives in the chipper tends to result in the throwing forward of a log being processed in the chipper, so that travel movement of the log is irregular and not controlled, and an irregular cutting action producing the chips results. In addition to producing problems in controlling log movement, localized wear regions in the chipper have resulted, together with a rough cutting action in the chipper.
A general object of the invention is to provide a slabbing chipper with novel structure controlling the depth of cut produced by knives in the chipper, making for a more uniform cutting action and more controlled movement of a log through the chipper.
Another object is to provide a slabbing chipper, with double-edged knives producing the cutting action, which includes detachable and replaceable wear plates associated with the knives functioning to establish a uniform depth of cut in the knives. The wear plates are easily removed and replaced when maintenance so requires.
In a preferred embodiment of the invention, the chipper includes a power-rotated head, with multiple knife structures distributed about the head. Each knife structure in the chipper includes a double-edged knife, disposed with an operative cutting edge moving in a substantially conical path in producing chips. A detachable clamp holds this knife in place with the clamp extending in covering relation over the nonoperative cutting edge in the knife. The clamp is surfaced by an outer wear surface, which during operation of the chipper, slides against the surface just cut by the cutting edge in the knife associated with the wear surface, to establish a preselected depth of cut with respect to a corresponding following knife in the chipper.
In a specific and preferred embodiment of the invention, the chipper may be provided with one or more detachable limiting plates, with wear surfaces on these plates moving in substantially a plane, with this plane paralleling but offset from a plane established by planing edges in the chipper.